Environmental Engineering Reference
In-Depth Information
large amounts of precipitation, most of which accumulates in a seasonal snow-
pack. They maintain that all the accumulated atmospheric deposition is delivered
in a very short period to the ground and receiving waters during spring snow-
melt. The presence of the noxious gases together with other airborne particulates,
ensures that the pH of rainfall onto the ground surface will be acidic. Spatial
variations in atmospheric deposition of acid solutes are the result of precipita-
tion amount in combination with concentration, and that deposition does not nec-
essarily relect variations in concentration alone (Nanus et al., 2003). Deposition
of airborne particulates with rainfall will also ensure that these will be carried
with the surface runoff and also with iniltrating water. The other causes of con-
tamination of precipitation recharge water include (a) runoffs and from polluted
land surfaces, as might be found on agricultural lands, and (b) iniltration into
subsurface through land surface polluted with pesticides, fungicides, other sur-
face wastes, organic debris, heaps, leach piles, sulide rock piles, etc. The evidence
shows that in regions where urbanization, industrialization, and exploitation are
present, it is dificult to ind precipitation recharge devoid of contaminants and
airborne contaminants. Furthermore, in these regions, it is also dificult to rule
out contamination of the receiving waters and groundwaters from contaminated
runoffs and iniltration. For regions remote from the effects of industrialization
and urbanization and also far remote from airborne contaminants, one would
have better chances of inding uncontaminated recharge precipitation. Treatment
of polluted or contaminated recharge precipitation is not generally practical since
it is more than likely that contamination already exists in the water and land
receptors in urbanized and industrialized regions. Instead, passive treatment
using natural processes together with aggressive treatment of extracted water are
used to provide safe drinking water (see Chapter 3).
• Improvement of Soil Quality for a Sustainable Soil Resource
: Soil is an important
resource material. It contains most of the nutrients required for plant growth and
is rich with microorganisms. Besides being the most critical medium for agricul-
tural food production and also production of other kinds of crops and trees such
as cotton and palm trees, it is also a very important tool for management of wastes
and waste discharges in the ground—as seen in the previous chapter. It serves as
a dynamic resource not only for production of food and raw materials, but also
for the soil microorganisms contained in the soil. These microorganisms not only
play an important role in the natural bioremediation of harmful organic chemicals
in the ground, they participate intimately in the recycling of carbon, nitrogen,
phosphorus, and other elements in the soil. In essence, they are signiicant con-
tributors to the control or management of greenhouse gases, water low in soils,
soil quality, and through all of these the life-support systems for humankind.
It is recognized that loss of nutrients, loss of biodiversity, loss of soil organics,
salinization, acidiication, and degradation of physical, chemical, and biological
properties of soil occur with time—through leaching processes, intensive agricul-
tural practice, erosion, and through overuse and poor land management. Natural
and/or man-assisted recharge of soil as a resource material—i.e., recharge of soil
quality—is required if sustainability of soil quality is to be achieved. We consider
recharge of soil quality
to consist of any or all of the types of physical, chemical, and
biological amendments, methods, and processes that serve to increase soil qual-
ity. Figure 13.2 shows a schematic description of soil quality changes with time.
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